In the parent application, a circular knitting machine is disclosed in which a stitch cam is supported for movable adjustment along an inclined angle relative to the needle raising cam for obliquely moving together an upper stitch cam member and a lower landing cam member to change the stitch forming level of the needles. Upper and lower needle raising cam members are integrally formed on a needle raising mounting block and have correspondingly upwardly inclined lower and upper butt engaging surfaces that are spaced from each other a distance substantially corresponding to the dimensions of the predetermined height of the needle butts to define an upwardly inclined closed track.
A stitch cam mounting block includes an upper stitch cam member and lower landing cam member having respective downwardly inclined lower and upper butt engaging surfaces being spaced from each other a distance substantially corresponding to the dimensions of the predetermined height of the needle butts to define a downwardly inclined closed track therebetween. The upwardly and downwardly inclined closed tracks form a triangular configuration when viewed in cross section.
In the illustrated embodiment of the parent application, the lower cam member also includes a downwardly inclined upper butt engaging surface extending from the top portion of the upwardly inclined upper butt engaging surface. This downwardly inclined surface cooperates with the lower landing cam member. The upper butt engaging surface of the lower landing cam member includes a front notch and the downwardly inclined upper butt engaging surface of the lower cam member includes a rear notch cooperating with the upper butt engaging surface for providing a continual butt engaging surface when the lower landing cam member is moved obliquely. The cooperating surfaces form a smooth transition for the lower surfaces of the needle butts when the stitch cam member is adjusted to change the stitch forming level of the needles.
At the apex of the formed triangle of the closed tracks, the lower butt engaging surfaces do not form a smooth transition. There are no continual butt engaging surfaces at the juncture of the upper raising cam member and upper stitch cam member. When the stitch cam is moved to change the stitch forming level of the needles, the spacing between the downwardly inclined upper and lower butt engaging surfaces changes, and the downwardly inclined upper and lower butt engaging surfaces do not remain substantially parallel. As a result, the needles sometimes do not pass through the closed track as accurately as desired, and knitting quality may be compromised. During high speed knitting operation, the needle butts could jam as they move from the upper cam member onto the downwardly inclined butt engaging surface of the stitch cam member.